1. Field of the Invention
The subject invention generally relates to a composition that has improved adherence with an addition-curable material. The subject invention also generally relates to a composite article that includes the addition-curable material and at least one substrate that is formed from the composition. The composition includes a resin component and an additive for reaction with the addition-curable material.
2. Description of the Related Art
Addition-curable materials and their uses are known in the art. It is desirable to use addition-curable materials because volatile byproducts are not generated during reactions to cure these materials. One example of an addition-curable material is a silicone-based elastomer that cross-links, upon cure, by hydrosilylation. Such materials are used, for example, in the automotive components industry for sealing or adhering various components together. During curing, the silicone-based elastomer also physically— and/or chemically-interacts with the chemical makeup of the various components to adhere or bond the components together. Frequently, the various components are typically formed from a polymeric composition. It is known that the interactions between the silicone-based elastomer and the polymeric compositions that make up the components are weak. As a result, the times and temperatures required to ensure adequate interaction between the elastomer and the polymeric composition are significantly higher than those required to cure the silicone-based elastomer. Often, it is preferred that the predominant interaction be chemical in nature to ensure durability of the bonded composite. However, even with extremely long cure times and/or extremely high cure temperatures, the chemical interaction between the silicone-based elastomer and certain polymeric compositions is not sufficient because there is no reactive chemical functionality present in these particular polymeric compositions for the addition-curable material, i.e., the silicone-based elastomer, to react with. Because there is no reactive chemical functionality present in the particular polymeric compositions, there is no reactive chemical functionality present at the surfaces of the components. As a result, the adhesion between silicone-based elastomer and the components is inadequate.
Furthermore, due to the high temperatures needed to develop adhesion with addition-curable materials, outgassing of entrained volatile materials, such as water from the polymeric compositions, leads to formation of undesirable voids or bubbles in the joint between the silicone-based elastomer and the substrate or substrates. This problem is particularly acute with hygroscopic, polar polymeric compositions such as polyesters, polyamides, polyimides, and epoxy resins. To overcome this limitation, the components often need to be pre-dried, requiring additional process steps and drying equipment in a manufacturing process.
In the art, there are many examples of external treatment methods for the surfaces of the components, such as application of a primer or exposure to high energy sources such as plasma, corona, or ultraviolet light. However, such treatment methods require additional processing time and/or costly equipment in the manufacturing process.
Due to the deficiencies associated with the silicone-based elastomers and polymeric materials of the prior art, including those described above, it would be desirable to provide a composition that has improved adherence with an addition-curable material, such as a silicone-based elastomer, while eliminating the need for pre-drying and external treatment methods of the surfaces of the components.